It is one way to do it. With the approach you suggested, it means going through this process:
  1. fetch an entry
  2. find any children
  3. for each child, call step 1
This requires multiple calls to the DB, which is likely to be slower than issuing one single call to find all descendants. The process of sending the query to the DB, having the DB parse the SQL, run the query, return the results, and parsing the results has to happen many more times (depending on the nature of your data) than with the structure I suggested.

It, too, is not without its problems though. For instance, keeping the two tables in sync can be tricky. The Nested Set Model of Trees describes a way to do it in a single table, and it is very fast for reads. But inserting a node into the tree can involve a large number of updates, so, depending on your data, it may not be applicable.

I think that there is no perfect solution - each one has its pros and cons, and has to be considered in the context of the type of data (and use of that data) that you have.

Clint

In reply to Re^3: message board thread quandary by clinton
in thread message board thread quandary by stonecolddevin

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